> Regarding iodepth, I am using 1 job with 1 outstanding IO - as stated in the specification - > to circumvent IO scheduler influences. I thought higher queue depths will always lead to > higher latencies, correct? (https://www.kernel.org/doc/Documentation/block/stat.txt) > Therefore testing with 1 nj/1 iod will generate comparable latency results, or not? In the report you have mentioned IO Depth of 16. Do you mean you set 16 for Throughput and IOPS test and then reduce the Depth to 1 for latency test ? While your statement about the impact of queue depth on the latency is make sense to me, it is hard to make a connection between IOPS numbers generated with IO Depth of 16 to Latency numbers generated with IO Depth 1. > Another question, is there a chance to turn off this cache? > It seems it is not the regular device write cache, as I turned it off with "hdparm -W" > and latencies seem to produce the same results (just on a quick test). I believe it is vendor specific, mostly drives don't honor such a requests or even cache flush requests. -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
